I'm currently doing some welding repairs, and as such will end up with a lot of bare metal or burnt back of welds in pretty much inaccessible locations. Some more or less sealed cavities, or some just very inaccessible say like a corner window scuttle. Or in behind a door hinge panel, sill cavities etc. What are the best options for poking something in to get some sort of protection applied to these areas ? TBH when I've cut the rust out and welded repairs in, it doesnt even look like the original parts had any protection in some areas because multiple layers had been stacked etc although the deeper layers had lasted fine.